Waveguides have conventionally been used for signal transmission in electronic devices. For example, there has been proposed a semiconductor device including a semiconductor chip and a waveguide that is formed thereabove or therebelow. This waveguide includes a transmitting antenna and a receiving antenna that are electrically connected to the semiconductor chip and that are not in contact with the waveguide.
See, for example, Japanese Laid-open Patent Publication No. 2008-148041.
Waveguides enable signal transmission with lower loss than planar transmission lines. However, these waveguides having conventional structures are large in size. Namely, it is difficult to manufacture small electronic devices including waveguides.